Thermosensitive polymer-modified gold nanoparticles with sensitive fluorescent properties

Highlights: • "Grafting through" method is used to fabricate thermosensitive polymer-modified GNPs. • All GNPs aqueous solutions but [email protected] exhibit LCST-type thermosensitivity. • Tunable fluorescence of polymer-modified GNPs has been achieved. Two types of thermosensitive polymer-modified gold nanoparticles (GNPs), P(DMAM-co-MADMAC)-modified GNPs ([email protected]) and P(NIPAM-co-MADMAC)-modified GNPs ([email protected]), are fabricated by the "grafting through" polymerization technique. The as-prepared GNPs are characterized by UV–vis, TEM, XPS, TGA, FT-IR and ¹H NMR spectroscopy. The thermosensitivity and fluorescence of the GNPs are investigated. It is found that all GNPs aqueous solutions but [email protected] exhibit thermosensitivity originated from thermosensitive polymer chains and sensitive fluorescence from the dimethylaminochalcone group. The lower critical solution temperature (LCST) of the GNPs decreases with the increasing content of MADMAC unit in the GNPs. The GNPs aqueous solution shows weak fluorescence after the temperature increases from 25 °C to 45 °C, or after β-cyclodextrin (β-CD) is added. Furthermore, it exhibits strong fluorescence when the solvent is changed to ethanol or chloroform, and the fluorescent wavelength undergoes a blue shift from ethanol to chloroform.